Gildas was a 6th-century British monk, missionary, and abbot who is primarily remembered as a significant historian of the sub-Roman period. Born in the Kingdom of Strathclyde, he abandoned a royal heritage to pursue a religious life after studying at the College of St. Illtud. He became a renowned teacher and missionary, traveling to Ireland to restore Christian order and later settling in Brittany. His most famous work, a religious polemic regarding the history of the Britons, remains a vital source for understanding the era of Saxon incursions.